In a large building, not far from the lens-house in which Roland Clewe had pursued the experiments which had come to such a disappointing conclusion, there was a piece of mechanism which interested its inventor more than any other of his works, excepting of course the photic borer.

This was an enormous projectile, the peculiarity of which was that its motive power was contained within itself, very much as a rocket contains the explosives which send it upward. It differed, however, from the rocket or any other similar projectile, and many of its features were entirely original with Roland Clewe.

This extraordinary piece of mechanism, which was called the automatic shell, was of cylindrical form, eighteen feet in length and four feet in diameter. The forward end was conical and not solid, being formed of a number of flat steel rings, decreasing in size as they approached the point of the cone. When not in operation these rings did not touch one another, but they could be forced together by pressure on the point of the cone. This shell might contain explosives or not, as might be considered desirable, and it was not intended to fire it from a cannon, but to start it on its course from a long semi-cylindrical trough, which would be used simply to give it the desired direction. After it had been started by a ram worked by an engine at the rear end of the trough, it immediately bean to propel itself by means of the mechanism contained within it.

But the great value of this shell lay in the fact that the moment it encountered a solid substance or obstruction of any kind its propelling power became increased. The rings which formed the cone on its forward end were pressed together, the electric motive power was increased in proportion to the pressure, and thus the greater the resistance to this projectile the greater became its velocity and power of progression, and its onward course continued until its self-containing force had been exhausted.

The power of explosives had reached, at this period, to so high a point that it was unnecessary to devise any increase in their enormous energy, and the only problems before the students of artillery practice related to methods of getting their projectiles to the points desired. Progress in this branch of the science had proceeded so far that an attack upon a fortified port by armored vessels was now considered as a thing of the past; and although there had been no naval wars of late years, it was believed that never again would there be a combat between vessels of iron or steel.

The recently invented magnetic shell made artillery practice against all vessels of iron a mere mechanical process, demanding no skill whatever. When one of these magnetic shells was thrown anywhere in the vicinity of an iron ship, the powerful magnetism developed within it instantly attracted it to the vessel, which was destroyed by the ensuing contact and explosion. Two ironclads meeting on the ocean need each to fire but one shell to be both destroyed. The inability of iron battle-ships to withstand this improvement in artillery had already set the naval architects of the world upon the work of constructing warships which would not attract the magnetic shell—which was effective even when laid on the bottoms of harbors—and Roland Clewe had been engaged in making plans and experiments for the construction of a paper man-of-war, which he believed would meet the requirements of the situation.

When Clewe determined to follow Margaret Raleigh's advice and give up for a time his work with the Artesian ray, his thoughts naturally turned to his automatic shell. Work upon this invention was now almost completed, but the great difficulty which its inventor expected to meet with was that of inducing his government to make a trial of it. Such a trial would be extremely expensive, involving probably the destruction of the shell, and he did not feel able or willing to experiment with it without governmental aid.

The shell was intended for use on land as well as at sea, against cities and great fortified structures, and Clewe believed that the automatic shell might be brought within fifty miles of a city, set up with its trough and ram, and projected in a level line towards its object, to which it would impel itself with irresistible power and velocity, through forests, hills, buildings, and everything, gaining strength from every opposition which stood in the direct line of its progress. Attacking fortifications from the sea, the vessel carrying this great projectile could operate at a distance beyond the reach of the magnetic shell.

Now that the automatic shell itself was finished, and nothing remained to be done but to complete the great steel trough in which it would lie, Roland Clewe found himself confronted with a business which was very hard and very distasteful to him. He must induce other people to do what he was not able to do himself. Unless his shell was put to a practical trial, it could be of no value to the world or to himself.

In one of the many conversations on the subject; Margaret had suggested something which rapidly grew and developed in Roland's mind.

“It would be an admirable thing to tunnel mountains with,” said she. “Of course I mean a large one, as thick through as a tunnel ought to be.”

In less than a day Clewe had perfected an idea which he believed might be of practical service. For some time there had been talk of a new railroad in this part of the State, but one of the difficulties in the way was the necessity of making a tunnel or a deep cut through a small mountain. To go round this mountain would be objectionable for many reasons, and to go through it would be enormously expensive. Clewe knew the country well, and his soul glowed within him as he thought that here perhaps was an opportunity for him to demonstrate the value of his invention, not only as an agent in warfare, but as a wonderful assistant in the peaceful progress of the world.

There was no reason why such shells should not be constructed for the express purpose of making tunnels. Nothing could be better adapted for an experiment of this kind than the low mountain in question. If the shell passed through it at the desired point, there would be nothing beyond which could be injured, and it would then enter the end of a small chain of mountains, and might pass onward, as far as its motive power would carry it, without doing any damage whatever. Moreover, its course could be followed and it could be recovered.

Both Roland and Margaret were very enthusiastic in favor of this trial of the automatic shell, and they determined that if the railroad company would pay them a fair price if they should succeed in tunnelling the mountain, they would charge nothing should their experiment be a failure. Of course the tunnel the shell would make, if everything worked properly, would not be large enough for any practical use; but explosives might be placed along its length, which, if desired, would blow out that portion of the mountain which lay immediately above the tunnel, and this great cut could readily be enlarged to any desired dimensions.

Clewe would have gone immediately to confer with the secretary of the railroad company, with whom he was acquainted but that gentleman was at the sea-side, and the business was necessarily postponed.

“Now,” said Clewe to Margaret, “if I could do it, I'd like to take a run up to the polar sea and see for myself what they have discovered. Judging from Sammy's infrequent despatches, the party in general must be getting a little tired of Mr. Gibbs's experiments and soundings; but I should be intensely interested in them.”

“I don't wonder,” answered Margaret, “that they are getting tired; they have found the pole, and they want to come home. That is natural enough. But, for my part, I am very glad we can't run up there. Even if we had another Dipsey I should decidedly oppose it. I might agree that we should go to Cape Tariff, but I would not agree to anything more. You may discover poles if you want to, but you must do it by proxy.”

At this moment an awful crash was heard. It came from the building containing the automatic shell. Clewe and Margaret started to their feet. They glanced at each other, and then both ran from the office at the top of their speed. Other people were running from various parts of the Works. There was no smoke; there was no dust. There had been no explosion, as Clewe had feared in his first alarm.

When they entered the building, Clewe and Margaret stood aghast. There were workmen shouting or standing with open mouths; others were running in. The massive scaffolding, twenty feet in height, on which the shell had been raised so that the steel trough might be run under it, lay in splinters upon the ground. The great automatic shell itself had entirely disappeared.

For some moments no one said anything; all stood astounded, looking at the space where the shell had been. Then Clewe hurried forward. In the ground, amid the wreck of the scaffolding, was a circular hole about four feet in diameter. Clasping the hand of a man near him, he cautiously peered over the edge and looked down. It was dark and deep; he saw nothing.

Roland Clewe stepped back; he put his hands over his eyes and thought. Now he comprehended everything clearly. The weight of the shell had been too great for its supports. The forward part, which contained the propelling mechanism, was much heavier than the other end, and had gone down first, so that the shell had turned over and had fallen perpendicularly, striking the ground with the point of the cone. Then its tremendous propelling energy, infinitely more powerful than any dynamic force dreamed of in the preceding century, was instantly generated. The inconceivably rapid motion which forced it forward like a screw must have then commenced, and it had bored itself down deep into the solid earth.

“Roland, dear,” said Margaret, stepping quietly up to him, tears on her pale countenance, “don't you think it can be hoisted up again?”

“I hope not,” said he.

“Why do you say that?” she asked, astonished.

“Because,” he answered, “if it has not penetrated far enough into the earth to make it utterly out of our power to get it again, the thing is a failure.”

“More than that,” thought Margaret; “if it has gone down entirely out of our reach, the thing is a failure all the same, for I don't believe he can ever be induced to make another.”